<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>外部 css </title>
</head>


<body>


    <link rel="stylesheet" href="mystyle.css">




    <h1>This is a heading</h1>
    <p>This is a paragraph.</p>


</body>

</html>